This invention relates to a multiple chamber hose suitable for drip irrigation and the like, and to a method of making such a hose.
Drip irrigation hose has been formed from continuous plastic strips for a considerable period of time, and there is a wide range of prior patents in the field. The most pertinent of these known to applicants are listed in the attached Information Disclosure Statement.
The various prior art hoses operate in the same general manner. A primary chamber is connected to the water supply, and the pressure in the primary chamber is relatively high. Some form of flow restriction devices are incorporated in or added to the hose for distributing water at spaced locations along the hose at a substantially reduced pressure. One problem in the manufacture and use of such hose is achieving and maintaining a desired stable low rate of flow from the restriction devices. Such irrigation hose is manufactured in rolls and is installed in very long lengths, with typical roll lengths in the range of 3,000 to 15,000 feet. Uniformity in the construction of the restriction device over thousands and thousands of feet of hose at high speeds has been difficult.
Another problem encountered with irrigation hose is the cost of manufacture, since large quantities of the hose are utilized and typically must be replaced every growing season. Therefore a design and method of manufacture which permits high speed production while at the same time maintaining precise control of the restriction devices is highly desirable.
Accordingly, it is an object of the present invention to provide a new and improved multiple chamber hose and a method of making such a hose which is less expensive, more accurate, and more reliable than present hose.
Another problem with many present manufacturing methods is that they require molding of plastic to establish the restricted flow paths. This usually is performed by melting plastic resins and forming the entire tube or by forming the secondary flow path from molten plastic and adding it to the cured plastic film while still in a semi-moltent stage. The cured film forms the main body of the tube. See for example the U.S. Pat. Nos. 4,534,515 and 4,572,756 to Chapin, and Mock U.S. Pat. No. 3,903,929. The above mentioned techniques are limited in rate of production due to the molten nature of the material and the necessary cure time. Uniformity of the restricting secondary chamber is an important consideration in hose manufacture because of its effect on uniform flow rates desired for the finished product in the field. In contrast the precision die cutting of the secondary chamber in the present invention provides exact repeatability with high rates of production. Further, deformation of the tube forming material with its accompanying uniformity problems is not required.
Other objects, advantages, features and results will more fully appear in the course of the description.